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    <meta charset="UTF-8" />
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    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>  
      // 输入：[1, 2, 4, 4, 3, 4, 3], 4
      // 输出：3
      let arr = [1, 2, 4, 4, 3, 4, 3];
      let item = 4;
      let num = 0;
      function count(arr, item) {
        for (let i = 0; i < arr.length; i++) {
          if (arr[i] == item) {
            num++;
          }
        }
        console.log(num);
      }
      count(arr, item);
    </script>
  </body>
</html>
